[Nexus 7 General] IIHomieII:
ok, I can help but you have to be very detailed, perhaps one function at a time will make it easier..

You said power on =

Do you mean when the device is powered by usb and/or stock charger?

or

Do you mean when the device is booted up?

Lets start with power on = connected to usb and/or stock charger.

If you have you power wiring whether it be usb or the stock charger on a ac/dc converter setup to only power when the key is on and turned to the accessory position (same as when the car is running) that is probably the best way to go but it depends on how you have your wiring.

In my case when I turn my key to accessory position or start the car (same thing) with or without tasker the screen comes on by itself, as you know any phone or tablet when plugged in turns on the screen, so no need for tasker there..

now once the screen comes on because you turned your key/started the car this is where tasker can come in to play..

I turn my key, the screen comes on and tasker is listening for the screen on event. Once the screen comes on whether the lock screen is used or not, my profile starts to do its thing all because of the screen on event,

SCREEN ON=

turn on wifi

turn on bluetooth

turn on whatever else I want, music etc..

You should start with just one of these because sometimes you might need to add a delay of just a few seconds between the things you are starting to make sure nothing skips/messes up etc.

Everything might work 9 out of 10 times without a few seconds delay between them but that 10th time it might mess up,,

so it should be like this:

SCREEN ON=

turn on wifi

wait 2 seconds

turn on bluetooth

wait 2 seconds

turn on music etc...

Once you get this going with just the first thing (wifi for example) then try adding the other things you want 1 at a time until its all flawless.,

If you are saying you want these things to happen at BOOT, not just when the screen comes on, let me know and we will see what the scenario is from there..

I only use the BOOT option to start POWERAMP 1 minute after the tablet has booted, since I want to use it as my media player, then I have it wait 2 seconds and tell it to go to the HOME SCREEN, so it is in the background and if I start music automatically from tasker it plays in POWERAMP and not any other player.

I then use the exit task for the same thing, when the tablet is no longer powered (I turned off the car/got out of the car with the keys) then I tell it to:

turn off wifi,

wait 2 seconds

turn off bluetooth

wait 2 seconds

run app called 'screen off and lock'

and that means from the time I pull my key out in about 10 seconds the screen goes blank/locks.

You can also have it stop your music if you are to lazy to do it yourself.

Depending on the vehicle, some will continue to power your windows, stereo, etc for up to 5 minutes after pulling the key out but only until you open any door, then it cuts power to your, windows, stereo etc. so when testing the power off profile, if you still see the lightning bolt/charging symbol after you remove your key then try opening the door..

As for the screen on option being red, here is why:

https://groups.google.com/forum/?fromgroups#!topic/tasker/yK2GT66ig1A

If you have your wiring set for charging at all times, I can tell you how to make it work for that too..

AGAIN BE DETAILED WHEN RESPONDING, the more detail, the more I can help.. are you rooted?